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PCB Trace and Via Currents and Temperatures
The Complete Analysis: 2nd Ed.

Table of Contents

 
  Dedication     iii
  Table of Contents     v
  Preface to First Ed.     ix
  Preface to 2nd Ed.     xi
  Technical Note: TRM     xiii
  Acknowledgements     xv
           
Part 0  BEFORE WE START     1
0 Sizing Traces     3
           
Part 1  BASIC CONCEPTS     5
1 Introduction and Historical Background 7
2 Materials used in PCBs   11
  2.1 Copper used in PCBs 12
2.2 Dielectrics used in PCBs   15
3 Resistance and Resistivity   19
  3.1 Resistivity   19
  3.2 Resistance   21
  3.3 Thermal Coefficient of Resistivity  22
  3.4 Measuring Resistivity 24
  3.5 Non-Destructive Measurements 26
4 Trace Heating and Cooling   29
  4.1 Trace Heating    29
4.2 Trace Cooling     30
4.3 Model of Trace Heating and Cooling 33
4.4 Role of Current Density   33
4.5 Measuring Trace Temperature   34
4.6 Temperature Curves   37
           
Part 2  EMPIRICAL STUDIES and SIMULATIONS 41
5 IPC Curves     43
  5.1 Measuring the Data   43
  5.2 IPC Curves   45
6 Thermal Simulations   53
  6.1 Modeling Traces   53
  6.2 The IPC Modeling Process 56
  6.3 Sensitivities: Layout Parameters 62
  6.4 Sensitivities: Material Parameters 70
  6.5 Voltage Drop   77
  6.6 Role of Current Density   77
  6.7 Conclusions   77
           
Part 3  SPECIAL TOPICS     79
7 Via Temperatures     75
  7.1 Background Information 81
  7.2 Thermal Simulation   82
  7.3 Experimental Verification 89
  7.4 Experimental Results   91
  7.4 Voltage Drops   93
8 Via Current Densities   97
  8.1 Single Via   97
  8.2 Multiple Vias     100
  8.3 Multiple Vias and Turn 102
  8.4 Conclusions   103
9 Fusing Currents, Background   105
  9.1 W. H. Preece   105
  9.2  I. M. Onderdonk   107
  9.3 Derivation of Onderdonk Equation 110
10 Fusing Currents, Analyses   119
  10.1 “Fusing” Time and Temperature 120
  10.2 Assumptions and Cautions 120
  10.3 Simulation Models   120
  10.4 Simulation Results   121
  10.5 Short-time Effects   124
  10.6 Final Conclusions   127
    Supplemental Comment   128
11 Fusing Currents, Empirical Testing 129
  11.1 Problems in Predicting Fusing 129
  11.2 The Fusing Process   131
  11.3 Experimental Results   132
  11.4 Summary     136
12 Do Traces Heat Uniformly?   139
  12.1 Thermal Gradients on Traces 140
  12.2 Thermal Gradients on Narrow Traces 141
  12.3 Parallel Investigation 142
  12.4 Does Trace Thickness Matter 142
  12.5 What Causes Thermal Non-Uniformity? 143
  12.6 Conclusions     143
13

AC Currents

  145
  13.1 Basic Models   145
  13.2 Experimental Verification   150
14 Thermal Effects; Right-Angle Corners   159
  14.1 Background   159
  14.2 Heating and Cooling Dynamics   160
  14.3 Experimental Verification   164
  14.4 Conclusions   166
15 Industrial CT Scanning   169
  15.1 Scanning Process   169
  15.2 Results     171
           
Part 4 APPENDICES     175
A1 Measuring Thermal Conductivity 177
A2 Measuring Resistivity   179
A3 Internal and Vacuum IPC curves   
    fitted with equations 191
A4 Detailed set of equations for the curves 195
A5 Internal and Vacuum IPC Curves 197
A6 Current Density in Vias   201
A7 Fusing Current Reference   211
A8 Fusing Current Simulations   213
A9 Non-Uniform Heating Patterns 217
           
  Abridged Index     219
           
  About the Authors     221
 

 


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